This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the Privacy Act 

5 USC §552a and has been cleared for distribution.

National Institute for Occupational Safety and Health

Response to Observations presented in “Evaluation of Internal Monitoring for 

Fission and Activation Products among INL Claimants (1949-1970), SCASEC-2015-0074-E2, Revision 0

Prepared by

W. Mitch Findley, CHP, MJW

Timothy D. Taulbee, PhD, CHP, NIOSH

February 25, 2016
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the Privacy Act 

5 USC §552a and has been cleared for distribution.

2

Introduction

The initial Evaluation Report (ER) for Special Exposure Cohort (SEC) Petition 00219 for the 

Idaho National Laboratory (INL) was issued by the NIOSH’s Division of Compensation 

Analysis and Support (DCAS) on March 12, 2015. DCAS presented the findings of the petition 

evaluation at the meeting of the Advisory Board on Radiation and Worker Health (ABRWH) in 

Richland, Washington on March 25, 2015. Subsequent to the this initial presentation a revision 

was made to the proposed SEC class definition due to the discovery of a change in external 

dosimetry practices in March 1970 and December 1974 which affected the SEC class definition. 

The ER was revised, issued on July 21, 2015, and presented at the meeting of the ABRWH in 

Idaho Falls, Idaho on July 23, 2015. The revised SEC class definition is:

All employees of the Department of Energy, its predecessor agencies and their 

contractors and subcontractors who worked at the Idaho National Laboratory 

(INL) in Scoville, Idaho, an (a) who were monitored for external radiation at the 

Idaho Chemical Processing Plant (CPP) (e.g. at least one film badge or TLD 

dosimeter from CPP) between January 1, 1963 and February 28, 1970; or (b) 

who were monitored for external radiation at INL (e.g. at least one film badge or 

TLD dosimeter between March 1, 1970 and December 31, 1974, for a number of 

work days aggregating at least 250 work days, occurring either solely under this 

employment, or in combination with work days within the parameters established 

for one or more other classes of employees in the Special Exposure Cohort.” 

(NIOSH 2015)

After the July 2015 meeting in Idaho Falls, Idaho, Sanford Cohen and Associates (SC&A) was 

tasked by the ABRWH with evaluation of the proposed SEC class definition for INL and to 

review the feasibility of dose reconstruction for the facilities and time periods evaluated. SCASEC-2015-0074-E2, Revision 0 “Evaluation of Internal Monitoring for Fission and Activation 

Products among INL Claimants (1949-1970)” was issued in October 2015 as part of the 

evaluation tasking requested by the ABRWH. In the summary section of the report, it states that 

“specific to internal dose reconstruction based on fission and activation product (FAP) bioassay 

indicator radionuclides, SC&A identified four major assumptions that form the basis for the 

determination that internal dose reconstruction is feasible for the relevant areas and time periods 

at INL that are not already covered by the proposed SEC class.” The four assumptions were:

1. FAP bioassays

2. FAP intakes

3. Actinide intakes

4. Special situations actinides
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the Privacy Act 

5 USC §552a and has been cleared for distribution.

3

The focus of the report was to only evaluate the FAP bioassays “related to the sufficiency of 

worker bioassay records for reconstructing doses to fission and activation products.” The 

evaluation produced the following three observations and summary recommendation:

Observation 1: SC&A agrees with NIOSH’s assertion that coworker models 

should be developed for the period of 1967-1970 for each relevant area under 

consideration.

Observation 2: Based on SC&A’s review of sampled claimants, it is not apparent 

that the lack of internal monitoring data is indicative of a lack of internal 

exposure potential. Given the uncertainty in establishing work areas, activities 

and ultimately exposure potential for claimants (particularly in the early years), it 

is recommended that coworker models be evaluated and developed for worker 

who were unmonitored, but like should have been monitored during all periods 

for which such exposures are possible.

Observation 3: Based on the examples provided in Table 5, it appears there are 

credible situations where it would be appropriate and claimant favorable to 

assign coworker intakes of FAPs and actinides to account for unmonitored 

portions of the claimants’ work history. Many of these examples predate the 

period currently identified by NIOSH as requiring a coworker evaluations (1967-

1970).

Summary Recommendation: Based on SC&A’s review of 92 randomly selected 

claimants, it was evident that FAP bioassay is generally available for a wide 

variety of job titles. Thus, SC&A does not believe there are “completeness” issues 

with the dataset of FAP bioassay that would preclude its use in developing 

coworker models. Nor was there any indication that specific job titles were 

systematically excluded from the internal monitoring program. However, it is 

SC&A’s opinion that FAP coworker models should be evaluated and developed 

for each relevant INL site area beginning with the start of radiological operations 

for each individual location. Though not directly related to FAP internal dose 

reconstruction, it is especially important to have reliable FAP data, because 

much of the internal alpha dose from the actinides will be based on Sr-90 or Cs137 intakes using Tables 5-22 or 5-23, respectively, or ORAUT-TKBS-0007-5 

(ORAUT 2010); as well as other FAP intakes based on ORAUT-OTIB-0054 

(ORAUT 2015).
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the Privacy Act 

5 USC §552a and has been cleared for distribution.

4

Discussion

In 1966, a joint decision by the Idaho Operations Office and Idaho Nuclear Corporation (prime 

contractor)1 was made to transition towards more reliance on in-vivo bioassay beginning in 1967. 

The new in-vivo program was a representative counting program such that workers were only 

counted every four years resulting in a net decrease in the number of in-vivo measurements at 

INL. This can be seen in Figure 1. 

In-Vivo Measurements for INL, 1961-1970

Year Number of Results

1961 1344

1962 2667

1963 3839

1964 1998

1965 2646

1966 3072

1967 1511

1968 1534

1969 1158

1970 1350

Figure 1: Data from Table 6-2 SEC00219 Evaluation Report2

There was also a significant drop in β/γ in-vitro bioassay as a result of this policy change. This is 

demonstrated in Figure 2 which lists the number of β/γ urinalyses for four separate areas at INL.

Except for the Chemical Processing Plant between 1963 and 1974, a data sufficiency issue was 

not identified during the SEC 00219 Petition evaluation. However it was determined that a 

bioassay co-worker mode was needed to support reconstructing internal dose post-1966 due to 

the transition away from in-vitro bioassay and a decreased in-vivo bioassay frequency.

 1 McCaslin, 1966, J. W. McCaslin Correspondence 1966; J. W. McCaslin; SRDB Ref ID 126064

2 Findley et.al., SEC Petition 00219 Evaluation Report revision 1, July 21, 2015
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the Privacy Act 

5 USC §552a and has been cleared for distribution.

5

Beta-Gamma Urinalysis by Area and Year at INL

Year CPP TRA Miscellaneous

Reactor Areas

CFA

1953 0 338 0 4

1954 403 668 0 196

1955 1029 1063 3 410

1956 1166 1822 80 386

1957 1729 3272 193 632

1958 1405 2701 291 303

1959 1298 3215 256 953

1960 645 3346 294 1225

1961 729 3286 606 1679

1962 807 3139 428 1277

1963 820 2912 208 1146

1964 998 2989 176 1177

1965 884 2297 142 1299

1966 222 1133 130 330

1967 11 47 0 111

1968 24 26 0 0

1969 19 19 0 0

1970 12 7 0 55

Figure 2: All data from SEC00219 Evaluation Report3: TRA data 

from Table 7.2, CPP data from Table 7-6, Misc. Reactor Areas 

from Table 7-11, and CFA from Table 7-14.

In the period after the issuance of the SEC 00219 Evaluation Report, there have been a number 

of personnel interviews performed by members of the ABRWH, SC&A, NIOSH, and the ORAU 

team. A couple of these interviews have provided new light on personnel monitoring practices 

which have caused reconsideration of limiting the INL coworker model for the year’s post-1966

(at this time the interview transcripts are not available yet for reference). The first interview was 

with a long-time health physics technician at INL who described the general practice of when a 

bioassay would typically be prescribed following work involving radioactive contaminants. In 

practice, contamination around the entry routes into the body (nose, mouth, wounds, etc.) or 

potential exposure to airborne radioactivity of concern would be placed on a follow-up “special” 

bioassay to determine if an intake of radioactive material had occurred and to aid in the 

 3 Findley et.al., SEC Petition 00219 Evaluation Report, Revision 1, July 21, 2015
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the Privacy Act 

5 USC §552a and has been cleared for distribution.

6

determination of the magnitude of the intake, if an intake had occurred. While this practice was 

typical it does leave open the possibility of a worker with radioactive contaminants on the hands 

introducing the material into the body inadvertently. This possibility would have existed since 

the beginning of radiological operations at INL. 

A second personnel interview involved a health physicist with responsibilities at the INL Burial 

Ground. During the interview the personal opinion was expressed that if there was one area that 

could have been improved upon during the earlier years at INL it would have been that more 

“biological samples” were taken. It was felt that internal dosimetry was not as well appreciated 

as external dosimetry at the time which is why there were not as many bioassay samples taken as 

there could have been. 

Conclusion

Based on new information obtained through recent personnel interviews, NIOSH believes it is 

appropriate to expand the INL coworker model to the beginning of radiological operations for 

each operational area of the site. This would allow for claimant favorable assignment of 

coworker intakes of FAPs and actinides to account for unmonitored portions of a claimants’ 

work history. NIOSH also believes that the existing bioassay would be bounding as it would 

include analytical data collected as a result of the highest potential intake scenarios. The fission 

and activation product coworker models would also take into account dose from alpha emitters 

as much of the internal alpha dose is based on ratios from Sr-90 and Cs-137 intakes.